Implementation of MS' sample code is apparently not straightforward. Based
on some material that turned up in the Google search engine for
"passfilt.dll", there may be some interactions between passfilt.dll and some
of NT's "system internals" that require a fair amount of savvy to handle. I
plan on looking into this a little further (when I can find the time); if
anyone's interested they can mail me direct.

I'm not sure I fully understand Alan's point wrt L0phtcrack etc., but I
don't believe password crackers obviate the utility of a tool such as
passfilt.dll.